Apparatus for cultivating crystals



June 11, 1940. E. GERLACH 2,204,180

APPARATUS FOR CULTIVATING CRYSTALS Filed July 13, 1937 FILTER SALT CRYSTALS 26 23 1 2 INVENTOR ATTORN EY Patented June 11, 1940 q UNITED STATES APPARATUS FOR CULTIVATIN G CRYSTALS Erwin Gerlach, Berlin, Germany, assignor to Telefunken Gesellschaft fii'r Drahtlose Telegraphic in. b. 11., Berlin, Germany, a corporation of Germany Application July 13, 1937, Serial No. 153,375

In Germany July 14, .1936

Claims.

This invention relates .to an apparatus for cultivating crystals-from solutions, more especially of producing piezo-elctric crystals from Rochelle salt.

5 There are various well known methods in obtaining crystals from salt solutions such as, for example, Rochelle salt crystals. The methods best known in the prior art are to obtain the crystals by placing them in standing baths or in rocking 1 baths.-

Such baths generally contain a saturated, heated solution which is introduced into vessels, and the culture crystals are suspended therein. The baths are provided with thermostats which are so controlled that the temperature of the solutions drops gradually. The thermostats for the baths are preferably adapted for placing the vessels containing the solutions into a heating liquid such as for example, water. 10 Both the rockingand standing bath methods require for obtaining crystals oi the desired size an extremely long time for proper growth extending through weeks and sometimes months.

In view of the extremely long time required for producing the crystals a continuous operation must be assured. If, for instance, the heating of the thermostats is interrupted for a brief period, the crystal introduced into the cultivation vessel would practically become useless, because of the successive process of crystallizing, wild crystals would, as a rule, be deposited on the culture crystal and would grow into each other.

In view of the long operating period necessary for producing the crystal, a large reserve in the standing and rocking bath is required. In fact, at the slightest disturbance the reserve equipment would have to take over for a long operating period the full operation for the baths.

Aside from the long duration required for producing crystals by the hitherto known methodsa rather high investment for these baths and appertaining drive arrangements is necessary.

According to this inventiomin order to accelcrate the growing or the crystals, and to assure independence of any incidental disturbances in the process, the following arrangement is proposed:

The solution for cultivating the crystals is prepared in one or several vessels. The vessels for the solution contain an excess in crystals. The

solution vessels communicate through-tube or vessel a separation of the salts of the culture crystal, a temperature difierence is sustained between the culture vessel and the solution vessel, whereby the solution vessel has a slightly higher temperature than the culture vessel.

The circulation for the continuous process is maintained in the liquid by passing it through the vessels by means of a pump.

In order to eliminate the use of a pump, the arrangement may also be such that the dinerent specific weights of the solutions in the solution vessel and culture vessel are utilized to as sure a natural circulation of the solution in accordance with the principle of the thermosyphon.

The vessels communicating with each other are built into a thermostat arrangement. Preferably, the entire arrangement is accommodated within a common thermostat, in which case the space containing the culture vessel or vessels is separated from the space containing the solution vessel or vessels by means of it well constructed of poor heat conduction materiaLso thata temperature diiierence between the solution vessel and the culture vessel can be maintained.

However, the solution vessels and the culture vessels may also-be set up separately in different thermostats. In this case, care is to be taken that the connection line between the vessels is sufliciently covered with material having a poor sary in the new method according to the invenwithin the tube lines betion. Thus, the arrangement may for instance be such that in the culture vessel the crystals are placed upon a conveyer band, whereby in cer-' tain instances the culture crystal is placed on the beginning of the band. In the latter arrangement, the crystal grows gradually and the band moves simultaneously through the culture vessel. The finished crystal can then be removed at the end of the band. The length of the band and itsspeed of movement depends on the size of crystal desired. I

The single iigureof the drawing shows an example of an arrangement for carrying out the method according to the invention for cultivating crystals from solutions.

' In a container I having a cover with material of poor heat conduction, a wall 2 is inserted which likewise consists of material having poor heat conduction and divides the said container into approximately two equal parts. The space- 3 contains a vessel 4 and accordingly the space 5 contains a vessel 6 having a cover. The vessels 4 and 6 communicate with each other through tube lines I and 8. Both vessels 4 and 6 are surrounded by a liquid 9 preferably water which is heated by an electric heating arrangement l0 and II. An additional heating arrangement I2 is provided for the space 3, whereby-the temperature of the liquid in space 3 can be maintained higher than in space 5. The heating arrangement in space 3 may also be rendered controllable by other well known methods. In order to avoid temperature drops in the liquid 9 within thespaces 3 and 5, elements l3 and I4 are provided for stirring up liquid 9 whereby the latter is continuously kept in motion.

In the vessel 4, a sieve-like tube 15 is inserted 'into which extends through .the bottom. l6

The vessel 4 has a cover 2| having an opening 22 through which vessel l5 extends into cover f2l. The vessel I5 is covered up by cover 23.

The tube 8- extends with a short end 24 into the vessel 4. At the end of tube 8 at point 24 a pump arrangement 25 is attached which is driven by said shaft 26, said pump 25 withdrawing the salt solution from the vessel 6. In order that the solution suctioned from vessel 6 has when entering the vessel 4 at the same temperature asthe solution contained in the vessel 4, the tube line 8 is formed ahead of the connection end 24 into a coil within vessel 3. Thus, the solution coming from the vessel 6 is preliminarily heated in tube 8 in such manner that it alreadyhas the temperature of the solution in vessel 4 when em I tering it. s

At the temperature within vessel 9 the solution leaving vessel 6 is practically saturated. After the solution has been heated in vessel 4 it can dissolve further crystals. is conducted past the cryst ls 20, then passes through the filter into tube and through the latterand tube 1 into vessel 6. The part of tube 1 within vessel 5 is "formed into a coil in order that the solution passing through tube 1 may assume the temperature in vessel 6. A culture crystal 21 is inserted into vessel 6. In order "to prevent temperature drops within the solution contained in vessel 6, the said solution is maintained in continuous motion within vessel 6 by means of a stirring up or agitator means 28. v

The solution leaving tube 1 and entering the vessel 6 is supersaturated since the temperature in vessel 6 is slightly lower than in vessel 4. The supersaturated solution gives up salt molecules which will be deposited on crystal 21.

The supplied quantity of solution for vessel Sis preferably controlled by means of pump 25 so that the liquid entering vessel 6 is of such quantity that the amount of salt molecules to be freed is just suflicient for deposition on crystal 21. It was found to beef advantage to accelerate cultivation. of the crystal by supplying with the grow- To this end, it

ing of the crystal a larger quantity of solution to vessel 6.

When the crystals become larger, the growth may eventually also be accelerated by slightly increasing the temperature difference between vessel 3 and vessel 5.

It is also possible to connect several solution vessels or culture vessels in parallel. It is also of advantage if the individual vessels can be shut off independently of each other. The arrangement may be such that several culture vessels are arranged about a larger solution vessel, for instance, in a circular position. It is preferred that each culture vessel can be shut off individually.

What is claimed is: r I

1. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, a vessel within each separate space, means for maintaining a saturated solution within said vessels, fluid communicating means between said .vessels and. passing through said wall, a heatingarrangement adjacent each vessel for-maintaining a temperature difference between said vessels, and means for filtering and continuously circulating said satu-. rated solution from one vessel to another.

2. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, a vessel within each separate space, means for maintaining a saturated solution within said vessels, fluid communicating means between said vessels v and passing through said wall, a heating arrangement adjacent each vessel for maintaining a temperature difference between said vessels, and a filler and a pump located within at least one of said vessels for continuously circulating said'saturated solution from one vessel to another.

3. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing intotwo separate spaces, means for maintaining a heated fluid within each separate space, a vessel within eachseparate space and surrounded by said heated fluid, means for maintaining a saturated solution within said vessels, fluid communicating means comprising a coiled tube be-' tween said vessels surrounded by said heated fluid ing into two separate spaces, means for maintaining a heated fluid within each separatespace,a-

vessel within each separate space and surrounded by said heated fluid, means for maintaininga saturated solution within said vessels, fluid communicating means between said vessels and passing through said wall, a heating space comprising separate heaters adjacent each'vessel for maintaining a temperature diiference between said vessels, and means for continuously circulating said saturated solution from one vessel :to another.

5. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, a first and a second vessel within each separate space, means for maintaining a' saturated crystal solution within said vessels, a sleeve-like vessel for holding a supply of salt within said first vessel, 9. filter 'within said sleeve-like vessel. two fluid communicating means between said first and second vessels and passing through said wall, at least one of said communicating means connecting said sleeve-like vessel and said second vessel, a heating arrangement adjacent said first and second vessels for maintaining atemperature difference there between, and means for continuously circulating said saturated solution from one vessel to another.

6. An arrangement for cultivating crystals comprising a casing, having a wall constructed of material of poor heat conductivity, said wall dividing said casing into two separate spaces, a first and a second vessel within each separate space, means for maintaining a saturated crystal solution within said vessels, at sleeve-like vessel for holding a supply of salt within said first vessel, a filter within said sleeve-like vessel, two fluid communicating means between said first and second vessels and passing through said wall, at least one of said communicating means connecting said sleeve-like vessel and said second ves sel, a heating arrangement adjacent said first and second vessels for maintaining a temperature difference therebetween, and means for continuously circulating said saturated solution from one vessel to another.

7. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, means for maintaining a heated fluid withinv each separatespace, a first and a second vessel within each separate space, means for maintaining a saturated crystal solution within said vessels, a sleeve-like vessel for holding a supply of salt within said first vessel, a filter within said sleevelike vessel, two fluid communicating means between said first and second vessels and passing through said wall, at least one of said communicating means connecting said sleeve-like vessel and said second vessel, a heating arrangement adjacent said first and second vessels for maintaining a temperature difference therebetween, and means for continuously circulating said saturated solution from one vessel to another.

8. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, a liquid within each separate .space, a vessel within each separate space and surrounded by said liquid, means for maintaining a saturated solution within said vessels, fluid communicating means between said vessels and passing through said wall, a heating arrangement adjacent each vessel for maintaining a temperature difference between said vessels, a filter and a pump located within at least one of said vessels, and. a plurality of agitators for continuously circulating said liquid in each separate space to prevent a temperature drop 'in said solution.

9. An arrangement for cultivating crystals comprising a'casing, a wall for dividing said casing into two separate spaces, a liquid within each separate space, a vessel within each separate space and surrounded by said liquid, means for maintaining a saturated solution within said vessels, fluid communicating means betwen said vessels and passing through said wall, a heating arrangement adjacent each vessel for maintaining a temperature difference between said vessels, a filter and a pump located within at least one of said vessels, an agitator for circulating said saturated solution within the other vessel, and a pluralityof agitators for continuously circulating said liquid in each separate space to prevent a temperature drop in said solution.

10. An arrangement for cultivating crystals comprising a casing, a wall for dividing said casing into two separate spaces, a liquid within each separate space, a vessel within each separate space and surrounding said liquid, means for maintaining a saturated solution within said vessels, fluid communicating means between said vessels and passing through said wall, a heating arrangement adjacent each vessel for maintaining a temperature difference between said vessels, a filter and a pump located within at least one of said vessels, and an agitator for circulating said saturated'solution within the other vessel.

ERWIN GERLACH. 

